Structural researches on the chelating behaviour of the biguanide ligand. The crystal structures of Co(C2H6N5)3 · 2H2O and Cu(C2H7N5)2CO3·4H20

Summary Crystals of the title compounds are both monoclinic, with unit cell dimensions:a = 9.293(5),b = 10.122(5),c = 16.737(7) Å. = 103.44(3)°,Z = 4, space groupP2₁/c for the cobalt derivative;a = 13.1ß5(7),b = 17.546(ß),c = 6.871(3) Å, = 107.01(4)°Z = 4, space groupP2₁/n for the copper derivative. The structures were solved from diffractometer data by the heavy-atom technique for the first compound and by direct methods for the second compound. Refinement by block diagonal least-squares gaveR = 5.9% for 3511 independent reflections andR = 8.8% for 2885 independent reflections for the cobalt and copper compound respectively. In both compounds the biguanide moiety behaves as a bidentate chelating ligand in a symmetrical tautomeric form, but it is deprotonated in the octahedral cobalt compound and neutral in the square planar copper compound.     

Cu(II) complexes with heterocyclic substituted thiosemicarbazones: the case of 5-formyluracil. Synthesis,characterization, x-ray structures,DNA interaction studies,and biological activity

Two new 5-formyluracil thiosemicarbazone (H(3)ut) derivatives, Me-H(3)ut (1) and Me(2)-H(3)ut (2), were synthesized by reacting thiosemicarbazides, mono- and dimethylated on the aminic nitrogen, with 5-formyluracil and were subsequently characterized. These ligands, treated with copper chloride and nitrate, afforded three complexes: [Cu(Me-H(3)ut)Cl(2)].H(2)O (3), [Cu(Me(2)-H(3)ut)Cl(2)].H(2)O (4), and [Cu(Me-H(3)ut)(NO(3))(OH(2))(2)]NO(3) (5). The crystal structures of these complexes have been determined by single-crystal X-ray diffraction. In 3 and 4, a similar pentacoordination is present; the copper atom is surrounded by the ligand SNO donor atoms and by two chloride ions. The structure of 5 consists of [Cu(Me-H(3)ut)(NO(3))(OH(2))(2)](+) cations and nitrate anions. The copper coordination (4 + 2) involves the SNO ligand atoms and a water oxygen in the basal plane; the apical positions are occupied by a second water oxygen and by an oxygen of a monodentate nitrate group. Two biochemical techniques, namely DNA titration in the UV-vis region and thermal denaturation, have been employed to probe the details of DNA binding of these compounds. Analysis of the results suggests that our compounds are able to interact with DNA by electrostatic and groove binding but not by intercalation. The compounds have been also tested in vitro on human leukemic cell line U937, but they are not able to inhibit significantly cell proliferation.     

Bosonization,topological solitons and fractional charges in two-dimensional quantum field theory

We further develop the quantization of topological solitons in two-dimensional quantum field theory in terms of Euclidean region functional integrals. Our approach is nonperturbative and mathematically rigorous. We apply it to construct physical states with fractional fermion number in models of interacting bosons and fermions without recurring to a semiclassical approximation. A related issue discussed in this paper is two-dimensional chiral bosonization.     

Structural and spectroscopic properties of 2-thiophenecarboxaldehyde 2-thienylhydrazone

In this paper the crystal and molecular structure of the title compound is reported. The crystals are monoclinic, P2₁/c,Z=4,a=13.406(4),b=5.367(1),c=15.545(6)Å,=110.00(5)°. The structure was solved by direct and Fourier methods and refined by full-matrix least squares toR=0.0497 andRw=0.0537 for 1094 unique reflections. The molecule shows an E-conflguration with respect to the C=N double bond. Mass and IR spectra are also discussed.     

Bis(triphenylphosphine)4-fluorobenzaldehyde thiosemicarbazone copper(I): Forcing chelation through oxoanions

This paper reports the synthesis and characterization of six compounds of copper(I), stabilized in its reduced state by two triphenylphosphines, in which 4-fluorobenzaldehyde thiosemicarbazone and N-methylthiosemicarbazone act as chelating through their sulfur and imino nitrogen. The three oxoanions that have been chosen, NO₃⁻, SO₄²⁻ and CH₃COO⁻, play an important role: their oxygens are bad competitors with the imino nitrogen of the thiosemicarbazone moiety and moreover they form strong charge assisted hydrogen bondings that stabilize the neutral form of the ligand. The overall packing is determined by intermolecular phenyl–phenyl van der Waals interactions.     

Heptacoordination in MnII,NiII, and CuII complexes of 2,6-diacetylpyridine bis (acetylhydrazone)

Manganese(II), nickel(II), and copper(II) complexes of 2,6-diacetylpyridine bis (acetylhydrazone) (H₂dapac) have been synthesized and structurally characterized by X-ray diffraction methods. [Mn(H₂dapac) (OH₂)₂](NO₃)₂ crystallizes in the monoclinic space groupP2₁/c witha=11.145(3),b=10.723(4),c=17.189(2) Å, =92.81(2)° andZ=4; [Ni(H₂dapac)(OH₂)₂] (NO₃)₂·H₂O crystallizes in the monoclinic space groupP2₁ witha=9.994(3),b=14.423(4),c=7.697(2)Å, =100.37(2)°, andZ=2; [Cu(H₂dapac)(OH₂)₂](NO₃)₂·H₂O crystallizes in the orthorhombic space groupPbcn witha=20.986(5),b=14.552(3),c=6.905(1)Å andZ=4. In each case the metal atom has a slightly distorted pentagonal bipyramidal environment, the equatorial positions being occupied by three nitrogen and two oxygen atoms from the hydrazone ligand and the apices by two water molecules. The crystalline cohesion in ensured by a three-dimensional network of hydrogen bonds involving the complex cations, the nitrate anions, and, where present, the uncoordinate water molecules.     

A Rigidity Result for Overdetermined Elliptic Problems in the Plane

Let be a (locally) Lipschitz function and a domain whose boundary is unbounded and connected. If there exists a positive bounded solution to the overdetermined elliptic problem we prove that Ω is a half‐plane. In particular, we obtain a partial answer to a question raised by H. Berestycki, L. Caffarelli, and L. Nirenberg in 1997.© 2017 Wiley Periodicals, Inc.     

Synthesis,characterization, crystal structure and antiproliferative in vitro activity of long-chain aliphatic thiosemicarbazones and their Ni(II) complexes

In the course of a research on metal-based compounds active on white blood cell cancers (leukemia, lymphoma and myeloma) nine aliphatic thiosemicarbazones and their nickel complexes have been synthesized with the aim to test their effect on histiocytic lymphoma U937 cell proliferation. All compounds were characterized by elemental, IR and NMR spectra analyses and for five of the complexes also by X-ray crystallography diffraction analysis. Heptanal thiosemicarbazone and the corresponding nickel complex were chosen after a solubility/stability test to carry out preliminary experiments in vitro on human leukemia cell line U937. The complex possesses a remarkable biological activity in inhibiting cell growth and in inducing apoptosis.     

New extremal domains for the first eigenvalue of the Laplacian in flat tori

We prove the existence of nontrivial compact extremal domains for the first eigenvalue of the Laplacian in manifolds ${\mathbb{R}^{n}\times \mathbb{R}{/}T\, \mathbb{Z}}$ with flat metric, for some T > 0. These domains are close to the cylinder-type domain ${B_1 \times \mathbb{R}{/}T\, \mathbb{Z}}$ , where B ₁ is the unit ball in ${\mathbb{R}^{n}}$ , they are invariant by rotation with respect to the vertical axe, and are not invariant by vertical translations. Such domains can be extended by periodicity to nontrivial and noncompact domains in Euclidean spaces whose first eigenfunction of the Laplacian with 0 Dirichlet boundary condition has also constant Neumann data at the boundary.